I currently have code that's trying to do some particle effects with the accumulation buffer, namely, a long degenerative motion blur.

The way I've got it now, I have the particles rendering to an auxiliary buffer, then it is put into the accumulation buffer, which applies a decay. The result is copied onto a second auxiliary buffer, then the back buffer is added into the accumulation buffer. Finally the result is put back onto the back buffer, the saved results are put from the second auxiliary back into the accumulation, and the back buffer is swapped to the front.

This seems to me to be not optimal, to say the least :D

Some others suggested using FBOs and vertex shaders to accomplish this, but I have no idea how to go about it. Any help?